Preheat your oven to 350°F (175°C) and prepare an 8-9 inch springform pan by lining the bottom with parchment paper and lightly greasing the sides.

In a mixing bowl, whisk together 2 cups of all-purpose flour, 2 teaspoons of baking powder, ½ teaspoon of salt, and 1 teaspoon of pumpkin pie spice (divided). Set it aside.

In an electric mixer, cream together ½ cup of unsalted butter and 1 cup of sugar on medium speed for about 3-4 minutes until light and fluffy. Add in two extra-large eggs one at a time, mixing well after each addition.

Gradually add the flour mixture into the creamed butter and sugar, mixing on low speed until just combined. Scrape down the sides of the bowl to ensure everything is well incorporated.

Evenly spread the batter in the bottom of your springform pan.

Slice 6-8 plums into eighths and arrange them decoratively on top of the batter.

Sprinkle the remaining tablespoon of sugar and the other teaspoon of pumpkin pie spice evenly over the arranged plums. Place the pan in the preheated oven.

Bake for about 45-55 minutes, until the cake is golden and a toothpick inserted into the center comes out clean.

Once baked, allow the cake to cool in the pan for about 15 minutes, then remove the sides of the springform pan and cool for another 10 minutes on a wire rack.